The object of the project is a greater understanding of the molecular microarchitecture of the vitreous. Specifically, the project is directed toward elucidation of the extent, stability, and structure of chain-chain interactions and other macromolecular associations in high molecular weight vitreous hyaluronic acid. A model system of low molecular weight hyaluronic acid fragments will be employed to characterize interactions in the absence of intramolecular chain segment associations. The extent of chain-chain association and the conformational changes accompanying interaction will be investigated by a variety of biochemical and biophysical methods. Specific methodology planned includes chromatography, viscometry, enzyme reactivity, proton exchange kinetics, and spectroscopy. The role of hydrogen bonds and/or specific ion effects in stabilizing intermolecular association will be determined. The model system data and assay techniques developed will be extended to studies on high molecular weight purified hyaluronic acid and to native vitreous hyaluronic acid. Additional studies employing a new electrophoretic technique, developed for the study of vitreous microarchitecture, will also be pursued. These investigations will determine the influence of concentration, molecular weight, and possible influence of other molecular species in the vitreous on hyaluronic acid interactions leading to the formation of a network-like matrix. Based on our understanding of vitreous structure and the stabilizing factors involved in chain association, efforts will be made to induce purified hyaluronic acid to more closely resemble the native vitreous properties.